Airborne exposure to wheat allergens: optimised elution for airborne dust samples

Well-validated methods for measuring airborne occupational allergens are essential for effective control and reduction of allergen exposures. For wheat flour allergens, specific immunoassays are available, but there is a need for optimisation and standardization of sample processing procedures. Wheat flour allergen elution and storage were studied using airborne dust samples collected in bakeries with a new parallel sampler. Forty-eight series of 9 parallel filters were subjected to extraction procedures varying in elution medium, shaking method, extraction vial, and centrifugation speed. Wheat allergens were measured with enzyme immunoassays, and the effect of various procedures evaluated by mixed regression analyses. The stability of the eluted allergens was assessed after storage for 20 days and 4 months at -20 degrees C, in the presence or absence of casein in the medium. Only the type of elution medium had significant effects on allergen recovery: addition of Tween-20 resulted in 3- to 100-fold increased levels, an effect that was most pronounced at low concentrations. Allergen levels in extracts were stable for at least 4 months at -20 degrees C, irrespective of the presence of casein in the medium. Addition of Tween-20 to the elution medium is essential for optimal extraction of wheat allergen. The recommended procedure further includes the use of conventional polystyrene tubes, simple shaking methods, and centrifugation after extraction. Wheat dust extracts in PBS-Tween can be stored frozen for at least 4 months, and addition of a stabilising protein is not required.     

Assessing joint toxicity of chemicals in Enchytraeus albidus (Enchytraeidae) and Porcellionides pruinosus (Isopoda) using avoidance behaviour as an endpoint

Contamination problems are often characterized by complex mixtures of chemicals. There are two conceptual models usually used to evaluate patterns of mixture toxicity: Concentration Addition (CA) and Independent Action (IA). Deviations from these models as synergism, antagonism and dose dependency also occur. In the present study, single and mixture toxicity of atrazine, dimethoate, lindane, zinc and cadmium were tested in Porcellionides pruinosus and Enchytraeus albidus, using avoidance as test parameter. For both species patterns of antagonism were found when exposed to dimethoate and atrazine, synergism for lindane and dimethoate exposures (with the exception of lower doses in the isopod case study) and concentration addition for cadmium and zinc occurred, while the exposure to cadmium and dimethoate showed dissimilar patterns.This study highlights the importance of dose dependencies when testing chemical mixtures and that avoidance tests can also be used to asses the effects of mixture toxicity.     

Vapor-phase concentrations of PAHs and their derivatives determined in a large city: Correlations with their atmospheric aerosol concentrations

Thirteen PAHs, five nitro-PAHs and two hydroxy-PAHs were determined in 55 vapor-phase samples collected in a suburban area of a large city (Madrid, Spain), from January 2008 to February 2009. The data obtained revealed correlations between the concentrations of these compounds and a series of meteorological factors (e.g., temperature, atmospheric pressure) and physical–chemical factors (e.g., nitrogen and sulfur oxides). As a consequence, seasonal trends were observed in the atmospheric pollutants. A “mean sample” for the 14-month period would contain a total PAH concentration of 13 835 ± 1625 pg m⁻³ and 122 ± 17 pg m⁻³ of nitro-PAHs. When the data were stratified by season, it emerged that a representative sample of the coldest months would contain 18 900 ± 2140 pg m⁻³ of PAHs and 150 ± 97 pg m⁻³ of nitro-PAHs, while in an average sample collected in the warmest months, these values drop to 9293 ± 1178 pg m⁻³ for the PAHs and to 97 ± 13 pg m⁻³ for the nitro-PAHs. Total vapor phase concentrations of PAHs were one order of magnitude higher than concentrations detected in atmospheric aerosol samples collected on the same dates. Total nitro-PAH concentrations were comparable to their aerosol concentrations whereas vapor phase OH-PAHs were below their limits of the detection, indicating these were trapped in airborne particles.     

Arsenic, chromium and mercury removal using mussel shell ash or a sludge/ashes waste mixture

Different batches of valued mussel shell and waste mussel shell ash are characterised. Shell ash has pH?>?12 and high electrical conductivities (between 16.01 and 27.27 dS?m^?1), while calcined shell shows pH values up to 10.7 and electrical conductivities between 1.19 and 3.55 dS?m^?1. X-ray fluorescence, nitric acid digestion and water extractions show higher concentrations in shell ash for most parameters. Calcite is the dominant crystalline compound in this ash (95.6 %), followed by aragonite. Adsorption/desorption trials were performed for mussel shell ash and for a waste mixture including shell ash, sewage sludge and wood ash, showing the following percentage adsorptions: Hg(II) >94 %, As(V) >96 % and Cr(VI) between 11 and 30 % for shell ash; Hg(II) >98 %, As(V) >88 % and Cr(VI) between 30 and 88 % for the waste mixture. Hg and As desorption was <5 % for both shell ash and the waste mixture, while Cr desorption was between 92 and 45 % for shell ash, and between 19 and 0 % for the mixture. In view of that, mussel shell ash and the mixture including shell ash, sewage sludge and wood ash could be useful for Hg(II) and As(V) removal.     

The influence of natural stressors on the toxicity of nickel to <Emphasis Type="Italic">Daphnia magna</Emphasis>

Global warming has become a source of awareness regarding the potential deleterious effects of extreme abiotic factors (e.g., temperature, dissolved oxygen (DO) levels) and also their influence on chemicals toxicity. In this work, we studied the combined effects of nickel and temperature (low and high levels) and nickel and low levels of DO to Daphnia magna, and concentration addition and independent action concepts as well as their deviations for synergism/antagonism, dose ratio and dose level dependency, were applied to survival and feeding rate data. Nickel single exposure showed an LC₅₀ value for 48 h of 7.36 mg l⁻¹ and an EC₅₀ value for feeding impairment at 2.41 mg l⁻¹. In the acute exposures to high and low temperatures, 50% of mortality was observed, respectively, at 30.7°C and 4.2°C whereas 50% reduction on the feeding activity was recorded at 22.6°C and 16.0°C. Relatively to low DO levels, a LC₅₀ value for 48 h of 0.5 mg l⁻¹ was obtained; feeding activity EC₅₀ value was 2 mg l⁻¹. On acute combined experiments, antagonism was observed for the combination of nickel and extreme temperatures, whereas a synergistic behaviour was observed in the combined exposure of nickel and low DO levels. At sublethal levels, nickel showed to be the main inducer of toxicity at high and low temperatures but not at low levels of dissolved oxygen. Toxicokinetics and toxicodynamics modelling studies should be made in the future to understand the toxicological pathways involved on complex combinations of stressors and to validate any conclusions.     

Host community attitudes towards solid waste landfill infrastructure: comprehension before compensation

One of the most controversial planning issues internationally is the siting of waste disposal infrastructure in local communities. Compensation is viewed as a possible solution to siting difficulties in many countries. However, existing empirical evidence is conflicting as to whether or not compensation-based siting has reduced opposition to such developments. Thus, before compensation policy can be considered as the solution for recognising social costs and introducing equity into the waste planning system, it is important to understand why people reject waste disposal infrastructure developments and if this rejection continues over the lifetime of facility operations. This paper utilises information gathered through surveys to examine the effects of distance, local authority consultation efforts, experience and other factors, on attitudes towards non-hazardous solid waste landfill developments in two examples of a potential and actual host communities. Our findings suggest distance proxies expectations of environmental risk in communities with no experience of living with landfill infrastructure. Community consultations by authorities are consistently important, even after a landfill has been in operation for a number of years. This suggests to policy makers to consult thoroughly and adequately before pursuing compensation policies.     

Dibenzothiophene desulfurization by Gordonia alkanivorans strain 1B using recycled paper sludge hydrolyzate

Enzymatic hydrolyzates of recycled paper sludge were tested as suitable feedstock for biological desulfurization by Gordonia alkanivorans strain 1B. Only the hydrolyzate obtained after enzymatic mixture dialysis (dialyzed hydrolyzate) allowed dibenzothiophene (DBT) desulfurization, in spite of faster bacterial growth did occur on non-dialyzed hydrolyzate. For dialyzed hydrolyzate, 250microM DBT was consumed after 96h displaying a maximum specific productivity of 2-hydroxybiphenyl of 1.1micromol g(-1)(dry cell weight) h(-1). A comparison of the kinetics of biodesulfurization was assessed according to the type of hydrolyzate supplementation. Complete consumption of DBT was observed upon the addition of only phosphates and ammonia although further addition of zinc did increase the 2-hydroxybiphenyl production by 14%. Strain 1B was able to desulfurize a model oil containing DBT, 4-methylDBT and 4,6-dimethylDBT, reducing by 63% the total sulfur content in 168h.     

Funneliformis mosseae and Invasion by Exotic Legumes in a Brazilian Tropical Seasonal Dry Forest

Russian Journal of Ecology - Parkinsonia aculeata and Prosopis juliflora are two of the most problematic invasive plant species in the Brazilian tropical seasonal dry forest, but the mechanisms...     

Determination of carbonyls and their sources in three sites of the metropolitan area of Costa Rica,Central America

Ambient levels of carbonyl compounds and their possible sources were studied at three places in the metropolitan area of Costa Rica, including a residential, an industrial, and a commercial downtown area with high vehicular flow, during the periods of April–May and September–December 2009. Fifteen carbonyl compounds were identified in the ambient air, of which acetone was the most abundant carbonyl, followed by formaldehyde and acetaldehyde. Concentrations were highest in rainy season at all sites and lower in dry season. These decreases in concentration are explained by the influences of both photochemical reactions and local meteorological conditions. The strong correlation between C1–C2 and C3 indicated a common origin for these carbonyls. The C1/C2 ratios varied between 0.49 to 1.05, values which can be considered typical of an urban area.